‘Life on a Young Planet: The First Three Billion Years of Evolution on Earth’ by Andrew Knoll

Life on a Young Planet presents a review of life on Earth from origins to the emergence of animals. The origin and evolution of life on Earth covers a vast range of scientific ideas from prebiotic chemistry to ancient climatology. Andrew Knoll successfully brings these seemingly disparate topics together into an engaging and well-structured account. The story is enlivened by the author’s personal experience, without overshadowing the main themes.

After providing the reader with a solid grounding in the relationship of organisms in the tree of life, the author takes us to the Proterozoic of Spitsbergen, explaining how we recognize and tease out information from the smallest preserved fossils to understand how they lived, before moving on to more challenging arguments for life in deep time in the Archaean rocks of Western Australia and South Africa. We then move even further back to the very beginning to discuss the origin of life, covering the different theories and the problems associated with life emerging from simple chemical beginnings. After this, the only way is up, and we head forward through time to review the emergence of more complex organisms; later chapters discuss the oxygenation of the atmosphere, emergence of eukaryotes and the Cambrian Explosion, ending with a brief look for life on other planets and the controversies of the Martian meteorite ALH84001. Throughout the book, the author emphasises the fundamental importance of life in shaping the physical and chemical evolution of the planet and the relationship between life and environment. This approach of always putting topics in an overall context prevents the book becoming just a set of facts, and by the end we have a strong idea of the ‘big picture’ in the tale of life on Earth.

Overall this is an engaging and entertaining read, and provides a good introduction to the subject for those new to it. Challenging concepts are explained in terms readily understandable to the non-specialist, although the book could perhaps benefit from a glossary of terms for quick reminders. Those already familiar with the subject will undoubtedly find new and surprising points of interest, which can be followed up using the key references listed for each chapter. Well illustrated throughout, sets of colour images help to bring lost worlds to life. Despite covering such a wide range of topics, all the necessary detail is provided. Contentious topics are dealt with in a balanced manner, with all sides of the arguments presented. This is a valuable and informative text for the astrobiologist.